Evolution of the fishtail-effect in pure and Ag-doped MG-YBCO

D. A. Lotnyk; R. V. Vovk; M. A. Obolenskii; A. A. Zavgorodniy; J. Kováč; V. Antal; M. Kaňuchová; M. Šefčiková; P. Diko; A. Feher; A. Chroneos

doi:10.1007/s10909-010-0198-z

paper

Evolution of the fishtail-effect in pure and Ag-doped MG-YBCO

arXiv:1006.4626 · doi:10.1007/s10909-010-0198-z

Abstract

We report on magnetic measurements carried out in a textured YBa $_{2}$ Cu $_{3}$ O $_{7 - δ}$ and YBa $_{2}$ (Cu $_{1 - x}$ Ag $_{x}$ ) $_{3}$ O $_{7 - δ}$ (at $x \approx$ 0.02) crystals. The so-called fishtail-effect (FE) or second magnetization peak has been observed in a wide temperature range 0.4~ $< T / T_{c} <$ ~0.8 for $H ∥ c$ . The origin of the FE arises for the competition between surface barrier and bulk pinning. This is confirmed in a non-monotonically behavior of the relaxation rate $R$ . The value $H_{ma x}$ for Ag-doped crystals is larger than for the pure one due to the presence of additional pinning centers, above all on silver atoms.

6 pages, 6 figures